Review

finding-13

/mubench/checkouts/asterisk-java/304421c/build/src/main/java/org/asteriskjava/util/Base64.java

base64ToByteArray(String, boolean)

class Base64 {
    private static byte[] base64ToByteArray(String s, boolean alternate) {
        byte[] alphaToInt = (alternate ?  altBase64ToInt : base64ToInt);
        int sLen = s.length();
        int numGroups = sLen/4;
        if (4*numGroups != sLen)
            throw new IllegalArgumentException(
                "String length must be a multiple of four.");
        int missingBytesInLastGroup = 0;
        int numFullGroups = numGroups;
        if (sLen != 0) {
            if (s.charAt(sLen-1) == '=') {
                missingBytesInLastGroup++;
                numFullGroups--;
            }
            if (s.charAt(sLen-2) == '=')
                missingBytesInLastGroup++;
        }
        byte[] result = new byte[3*numGroups - missingBytesInLastGroup];

        // Translate all full groups from base64 to byte array elements
        int inCursor = 0, outCursor = 0;
        for (int i=0; i<numFullGroups; i++) {
            int ch0 = base64toInt(s.charAt(inCursor++), alphaToInt);
            int ch1 = base64toInt(s.charAt(inCursor++), alphaToInt);
            int ch2 = base64toInt(s.charAt(inCursor++), alphaToInt);
            int ch3 = base64toInt(s.charAt(inCursor++), alphaToInt);
            result[outCursor++] = (byte) ((ch0 << 2) | (ch1 >> 4));
            result[outCursor++] = (byte) ((ch1 << 4) | (ch2 >> 2));
            result[outCursor++] = (byte) ((ch2 << 6) | ch3);
        }

        // Translate partial group, if present
        if (missingBytesInLastGroup != 0) {
            int ch0 = base64toInt(s.charAt(inCursor++), alphaToInt);
            int ch1 = base64toInt(s.charAt(inCursor++), alphaToInt);
            result[outCursor++] = (byte) ((ch0 << 2) | (ch1 >> 4));

            if (missingBytesInLastGroup == 1) {
                int ch2 = base64toInt(s.charAt(inCursor++), alphaToInt);
                result[outCursor++] = (byte) ((ch1 << 4) | (ch2 >> 2));
            }
        }
        // assert inCursor == s.length()-missingBytesInLastGroup;
        // assert outCursor == result.length;
        return result;
    }

}